Mining apparatus



Jan. 11, 1966 M. c. POTTS ETAL 3,228,300

MINING APPARATUS 2 Sheets-Sheet 1 Filed May 22, 1963 FIG].

SEQUENCE STOPPAGE HYDRAULIC CONTROL VALVE INDICATOR PRESSURE SOURCEHYDRAULIC PRESSURE SOURCE IN E'hToKS Mia/M L C. 7 07 73 DooSLAs H-H- B./T Y M M,

Jan. 11, 1966 M. c. PoTTs ETAL MINING APPARATUS 2 Sheets-Sheet 2 FiledMay 22, 1963 M/Cl/AEL a PZ T DOUGLAS H. H. BOLTON 3 BY ATTORN at UnitedStates Patent 3,2285% MlNlNG APPARATUS Michael Charles Potts, Presthury,Cheltenham, and Douglas Herbert Hewlett Bolton, Winchconihe, nearCheltenharn, England, assignors to Dowty Mining Equipment Limited,Ashchurch, near Tewkeshury, Gloucester, England, a British company FiledMay 22, 1963, Ser. No. 282,3% Claims priority, application GreatBritain, May 25, 1962, 2il,l98/62 8 Claims. (til. 91-1) This inventionrelates to roof support assemblies for use in mines.

The roof support assembly with which this invention is concernedincludes a series of roof supports distributed along the working face ofa mine, and each including one or more props extendable by fluidpressure against the roof to support the same, and contractible in likemanner. During normal operation the prop is first contracted from itsnormal roof-supporting condition preparatory to undergoing an advance.Its contraction, its subsequent advance, its normally ensuing extensionto reset it in the advanced position against the roof, and thetransmission of a signal to the next-to-be-advanced roof support, areall accomplished automatically by fluid pressure controlled by mechanismthat in its details is not a part of this invention. There may be somefailure to follow the normal sequence of operations, from one cause oranother, and if this occurs the sequence of operations ceases. Since theseries of roof supports extends for quite a distance along the workingface, whereas the operator is stationed at one end of the series and isunable to observe any stoppage, it is important that he be advised,immediately and automatically, so that he can take necessary stepspromptly, leading to correction of the cause of failure and resumptionof the automatic operation of the system. The present invention isconcerned, in such a system, with indicating means automaticallyoperable to indicate a stoppage to the operator, actuated, in the formshown herein, by the existence of a predetermined pressure in a pressureline that is part of the system, for more than a predetermined period oftime, whenever the series of roof supports is undergoing an advancingsequence.

The indicating means may indicate the existance of a maximum pressure inthe pressure line for more than the predetermined time when the seriesof roof supports is undergoing an advancing sequence, or it may indicatethe existence of a predetermined low pressure in the pressure line formore than the predetermined time when the series of roof supports isundergoing an advancing sequence.

The support advancing means may include a hydraulic pilot line connectedto a control valve of each roof support in turn, said control valveseach closing the pilot line before an advancing sequence commences,being actuated by receipt of a hydraulic-pressure signal in the pilotline from the previous support in the series, to cause its roof supportto undergo an advancing operation and opening the pilot line to nextsupport upon completion of the advancing operation of its own roofsupport.

When the indicating means is of the type to indicate existence of themaximum pressure in the pressure line for more than the predeterminedperiod of time, the absence of a pressure in the pilot line may bearranged to render the indicating means inoperative.

The indicating means may include a device responsive to pressure in thepressure line, the device being arranged to actuate an electricalcircuit, including an indicating device, when the pressure reaches thepredetermined value.

One embodiment of the present invention will now be 3,2233% PatentedJan. 11, 1966 ice described, by way of example, with reference to theaccompanying drawings, of which,

FIGURE 1 is a diagrammatic view of mining apparatus, 'but with thehydraulic connections and roof bars omitted,

FIGURE 2 is a similar view on a larger scale showing the hydraulicconnections,

FIGURE 3 is a diagrammatic view of the stoppage indicating means, and

FIGURE 4 is a diagrammatic view of the hydraulic control valve assemblyof a roof support.

With reference to FIGURES 1 and 2 of the accompanying drawings, miningapparatus includes a conveyor 1 extending along the working face 2 of acoal mine and a cutter 3 which passes along the working face 2 and issituated between the Working face 2 and the conveyor 1. The conveyor 1acts as a guide means for the cutter 3. The mining apparatus alsoincludes a roof support assembly located on the opposite side of theconveyor 1 to the cutter 3 and working face 2. The roof support assemblyincludes a series of roof supports 4 arranged along the working face 2,.Each roof support 4 includes a groundengaging sole beam 5 carrying threehydraulicallyoperable telescopic props 6, and the three props 6 carry aroof beam (not shown). Each roof support 4 is connected to the conveyor1 by a hydraulically-operable jack '7 for advancing the roof support 4towards the conveyor 1, and every fourth roof support 4 has a furtherhydraulically-operable jack 8 for advancing the conveyor 1 relative tothe roof support 4.

The mining apparatus also includes a hydraulic power unit 9 which has amain pressure source 10 from which a hydraulic pressure line 11 and ahydraulic return line 12 extend along the working face 2. Each roofsupport 4 includes a hydraulic control valve 13, details of which willbe given later, to which the pressure line ill and return line 12 areconnected by lines 14 and respectively. The control valve 13 of eachroof support 4 is connected to its props 6, jack 7 and jack 8 (ifprovided). The control valve 13 of each roof support provided with ajack 8 is so arranged that the jack 8 is urging the conveyor 1 towardsthe coal face continually except when the roof support 4 is beingadvanced. Actuation of the control valve 13 causes the followingoperations to take place in sequence:

(a) The jack 8 (if provided) is caused to cease pushing the conveyor 1forwardly,

(b) The props 6 are contracted to release the roof support from theroof,

(c) The jack 7 is caused to advance the roof support up to the conveyor1,

(d) After support advance has been completed, the jack 7 is caused tocease urging the roof support forwardly, the props 6 are extended toreset the roof support against the roof and the jack 8 (if provided) iscaused to resume pushing the conveyor 1 forwardly.

Actuation of the control valves 13 is caused by a hydraulic pilotsystem. The power unit 9 includes a source which in FIGURE 2 isdesignated 16, of hydraulic pressure for the pilot system, and a pilotline 17 extends from the pilot source 16 and passes through the controlvalve 13 of each roof support 4 in turn. Each control valve initiallycloses the pilot line 17. When the pilot source 16 is operated topressurise the pilot line 17, the hydraulic pressure in the pilot line17 acts as a signal to the control valve 13 of the first roof support 4.This roof support 4 undergoes an advancing operation, as described aboveand when the roof support has been satisfactorily reset against theroof, the satisfactory resetting being sensed by the attainment of adesired hydraulic pressure in the props 6, the control valve 13 iscaused to 3 open the pilot line so that the hydraulic pressure signal isthen applied to the control valve 13 of the next roof support, whichthen undergoes an advancing operation.

Thus each roof support in turn undergoes an advancing operation. Thehydraulic circuit relating to the advancing sequence is described inUnited States application Serial No. 282,760, filed May 23, 1963, and inUnited States application Serial No. 355,769, filed March 30, 1964.

The operation of the valve assembly 13 of each roof support 4 will nowbe described with reference to FIG- URE 4. The valve assembly 13 of aroof support 4 with a double-acting jack 8 includes six valve units A,B, C, D, E and F. Valve unit A controls the supply of hydraulic fluid tothe jack 8 in a jack-extending sense and is connected to the branchsupply line 14 and to a line 53 leading to the jack 8. Valve unit B isconnected to the line 53 and to the branch return line 15.

Valve unit D controls the supply of hydraulic fluid to the jack 7 andjack 8 in a jack-contracting sense and is connected to the branch supplyline 14 and to a line 54 leading to the jacks 7 and 8. Valve unit C isconnected to the line 54 and to the branch return line 15.

Valve unit E controls the supply of hydraulic fluid to the props 6 andis connected to the branch supply line 14 and to the props 6 through aline 55 including a restrictor 56 and a non-return valve 57. Valve unitF controls the release of hydraulic fluid from the props 6 and isconnected to a line 58 leading from the props 6 and to the branch returnline 15. The line 58 includes a nonreturn valve 59, and a pressurerelief valve 61 is connected in parallel with the valve unit F betweenthe line 58 and the branch return line 15.

The valve units A and B are associated with a pivotallymounted lever 62which is connected to a similar lever 63 associated with the valve unitsC and D. The levers 62 and 63 coordinate the action of valve units A, B,C and D. In those roof supports without a double-acting jack 8, valveunits A and B and lever 62 are omitted. The action of valve units E andF are coordinated by a pivotally-mounted lever 64. The levers 62, 63 areganged to one another as shown by the connection 60.

The valve assembly of each roof support 4 includes a pilot valve 65which, before an advance of the roof support begins, closes the pilotline 17. The pilot valve 65 includes a valve member 66 urged towards avalve seat 67 by a spring 68, and also includes a piston 69 carrying apiston rod 71. The piston 69 can be moved against the force exerted by aspring 72 by a sufiicient hydraulic pressure in a line 73 to cause thepiston rod 71 to lift the valve member 66 off the valve seat 67. Theline 73 is connected to line 55. The piston rod 71 has a bore 75 which,when the piston rod 71 is not engaging the valve member 66, brings oneside of the valve member 66 into communication with the branch returnline 15. When piston rod 71 engages the valve member 66, the valvemember 66 closes the bore 75.

Four non-return valves 76 are connected in the pilot line 17 to enablethe roof support to be caused to undergo an advancing operation by thereceipt of a signal along pilot line 17 from the adjacent left hand roofsupport or from the adjacent right hand roof support. A small restrictor74 is connected in the pilot line 17 across pilot valve 65 to ensurethat pressure cannot be trapped in the portion of pilot line 17 betweenvalves 76 and valve unit C by providing a leak to the branch return linethrough the bore 75 in piston rod 71.

A prop resetting valve 83 is associated with the support-advancing jack7. The resetting valve 83 includes a valve member 84 urged by a spring85 into a valve seat 86 to isolate the chamber 87 of the jack 7 from aline 88 connected to valve unit F and to line 55 through a nonreturnvalve 89. A lifter rod 91 can be moved to lift the valve member 84 oifits seat 36, as the jack 7 becomes contracted to the full extentintended, by a trip 93 carried by the piston rod 94 of the jack 7.

FIGURE 1 shows the cutting machine 3 traveling from left to right alongthe working face 2. After the cutting machine 3 has passed the first fewroof supports 4 in the series, it is necessary to advance the conveyor 1in front of these roof supports 4 and then to advance the roof supports4. Each roof support 4 having a conveyoradvancing jack 8 is operated tocause the jack 8 to apply an advancing force to the conveyor 1, the roofsupport 4 being set against the roof and acting as an anchorage. This isachieved by pivoting lever 62 is an anticlockwise direction to openvalve unit A and thus pressurizing the line 53 and the pushing side ofjack 8. This movement of the lever 62 may be caused by manual operationof lever 62 or by pressurization of a hydraulic line 95 connected tovalve unit B. The line 95 may be connected through a manually orremotely controlled valve to the main supply line 11. After the lever 62has been pivoted in the anticlockwise direction to cause the jack 8 tobe pressurized in the conveyor-advancing sense, a springoperated latch96 holds the lever 62 in this position. The anticlockwise movement oflever 62 causes a similar movement of lever 63, but such movement doesnot change the state of valve units C and D from that shown in FIGURE 4.The latch 96 is connected to the pilot line 17 in such a manner thatpressurization of the pilot line 17 releases the latch 96 so that valveunit A closes and returns lever 62 and consequently lever 63 to theposition in FIGURE 4.

When the first portion of the conveyor 1 has been advanced, as shown inFIGURE 1, the roof supports 4 can then be advanced. The source 16 isoperated to pressurize the pilot line 17 and hence a hydraulic pressuresignal is sent along line 17 to the first roof support 4. Referring nowto FIGURE 4, the hydraulic pressure signal reaches the roof supportthrough the portion of line 17 shown in the upper left-hand part ofFIGURE 4. The hydraulic pressure signal releases the latch 96 andoperates on valve unit C to cause clockwise movement of levers 62 and63. As a result, valve unit A closes, valve unit B opens, valve unit Ccloses and valve unit D opens. Thus the pushing or jack-extending sideof jack 8 is connected to the branch return line 15, and thejackcontracting sides of the jacks 7 and 8 are connected through theline 54 with the branch supply line 14. The conveyor-advancing jack 8 isnot actually connected to the conveyor 1 but merely pushes against theconveyor 1 when applying an advancing force to it. Therefore, at thisstage, the jack 8 contracts and takes no part in advancing the support.

Line 54 is also connected by a line 99 to valve unit F, and thepressurization of line 54 causes the valve unit F to be opened to bringthe line 58 into communication with the branch return line 15, thusreleasing the hydraulic pressure in the props 6 and so releasing theroof support 4 from the roof. The jack 7 then contracts and advances theroof support 4 towards the conveyor 1 with the conveyor 1 acting as ananchorage.

When the jack 7 is contracted to the full extent intended, or in otherwords when the roof support is fully advanced up to the conveyor 1, thetrip 93 on the piston rod 94 of the jack 7 engages the lifter rod 91 andopens the resetting valve 33. The line 38 is therefore brought intocommunication with the main supply line 11 through the branch supplyline 14, now-open valve unit D, line 54, jack 7 and resetting valve 83.The pressure in line 88 acts upon valve unit F to close it and thenpasses through nonreturn valve 89, restrictor 56 and nonreturn valve 57to extend the props 6 and so reset the roof support 4 against the roof.

The hydraulic pressure in line 88 is also present in line 73. When theprops 6 have been extended to give a statisfactory roof-supportingforce, as evidenced by a buildup of pressure in line 73 to apredetermined value, this value of pressure is arranged to operate onthe piston 69 and to open pilot valve 65. Thus the portion of the pilotline 17 between the control valve 16 and the first roof support 4 isbrought into communication with the portion of the pilot line 17 betweenthe first roof support and the second roof support (that is the portionof the pilot line 17 in the lower left portion of FIGURE 4) with theresult that the hydraulic pressure signal in the pilot line 17 reachesthe second roof support in the series and causes it to undergo anadvancing operation. In this way, each roof support in the group inadvanced in turn.

If it is desired to operate the valve assembly 13 manually, this can bedone by manually operating levers 62, 63, 64.

The mechanism so far described is not conventional, but is known, andhas associated with it various mechanisms and controls, of which thepresent invention is one. This invention adds to the hydraulicallyoperated basic system for automatic sequential advance of the roofsupports a means to indicate a stoppage in an advancing sequence, as aresult of some fault or abnormality; for it is most important that theoperator be warned so that he can take necessary corrective orprecautionary measures at once, leading eventually to correction of thefault and resumption of the automatic sequential advance of the roofsupports in the series. Absent such warning, the mine roof lacks supportas near as possible to the working face. If the roof supports do notadvance when they should, operation of the cutter 3 and the conveyor 2may have to be stopped immediately, and thus it is important, incarrying out the mining operation safely, that a stoppage in anadvancing sequence should be brought to the attention of an operatorsoon as possible.

While an advancing sequence is taking place, the pressure in the mainpressure line 11 will fluctuate as the various props and jacks areoperated in the sequence, and maximum pressure, if attained at allduring an advancing sequence, will only be attained for short periods.The pressure in the pressure line 11 will only be able to build up toand remain at maximum pressure, during an advancing sequence, if theadvancing sequence stops before it is completed, for example by reasonof a fault in a roof support or an obstruction preventing the advance ofa roof support.

In accordance with this invention, a sequence stoppage indicating means18 includes a pressure gauge 19 which is connected to the main pressureline 11 so as to indicate the pressure in it. The pressure gauge 19 hasa pointer 21, which forms a movable contact in an electrical circuit. Afixed contact 22 is located in the pressure gauge 19 at a position whichcorresponds to the position of the pointer 21 when the pressure in thepressure line 11 is the maximum. The electrical circuit also includes abattery 23 and an audible and/ or visual warning device 24 whichincludes a conventional false start time delay and relay so that thedevice 24 is only actuated if the circuit is closed for more than apredetermined period of time, for example thirty seconds.

A hydraulic-pressure-operated electrical switch 25, biased to open, isalso included in the electrical circuit and is connected to the pilotline 17 by a hydraulic line 26, so that a pressure in the pilot line 117will be transmitted to the switch 25 so as to close it.

When no advancing sequence is taking place, there is no pressure in thepilot line 17 and therefore switch 25' is open and the warning device 24cannot be operated even though the pressure in the pressure line illlmay be maximum for a considerable time.

When an advancing sequence is taking place, the pilot line 17 ispressurized and this pressure is transmitted along line 26 to closeswitch 25. Each time the pressure in the pressure line 11 reaches themaximum, the pointer 21 engages the contact 22 and completes thecircuit. However, temporary attainments of maximum pressure which mayoccur in the pressure line 11 during an advancing sequence will notcause the closure of the circuit since the time delay device at 24permits closure only if the maximum pressure persists for more than thepre determined period of time.

The warning device 24 only operates if, during an advancing sequence,the pressure in the pressure line 11 remains at maximum for more thanthe predetermined period of time. As explained above, this can onlyhappen if the advancing sequence stops before it is completed and,therefore, the operator is warned of such an event.

If the power unit 10 fails or a serious leak occurs in the hydrauliccircuit, an advancing sequence may stop. Such a leakage will cause thepressure in the main pressure line 11 to fall to and remain at a lowvalue. The pressure in the pressure line 11 may fall to such a low valuefor short periods during an advancing sequence, for example when theprops 6 are being reset, and, therefore, only a low pressure for morethan a predetermined period of time will indicate failure of thehydraulic system by leakage or failure of the power unit 10.

The pressure gauge 19 includes a contact 27 which is engaged by thepointer 21 if the pressure line 11 falls below a predetermined value.The contact 27 is connected to the warning device 24 by a connectionwhich bypasses the switch 25. Therefore, the circuit to the warningdevice 24 will be completed eace time the pressure in the pressure linefalls to the predetermined low value, but due to the delay included inthe device at 24, the Warning device 24- will only operate if the lowpressure is present for more than the predetermined period of time.

The operation of the warning device 24 by the occurrence of low pressurein the pressure line 11 is independent of the switch 25, that is to sayif low pressure occurs for more than the predetermined period of time,the warning device 24 will operate whether an advancing sequence was inprogress or not.

We claim:

1. A roof support assembly including a series of fluidpressure-operatedadvanceable roof supports, a source of fluid pressure, a conduitconnecting said source with each roof support, each roof supportincluding at least one fluid-pressure-operated prop to which saidconduit is connected, and a fluid-pressure-operated means to advance italso connected to said conduit, and a control valve assembly individualto each roof support and operable to supply pressure fluid from suchsource to cause its roof support to undergo an advancing operation, eachcontrol valve assembly being arranged to send a signal to the controlvalve assembly of the next roof support, to initiate advance thereof,upon completion of the advance of its own roof support, a Warning deviceincluding a pressuresensitive means operatively connected to saidconduit, and operable by departure of pressure therein from its normalrange fluctuation occurring during an advancing operation, to indicateinterruption of such operation, and time delay means operativelyconnected to said indicating means to delay its indication during suchnormal pressure fluctuations, but effecting such indication in the eventof a continuing abnormal pressure in said conduit.

2. A roof support assembly including a series of fluidpressure-operatedadva'nceable roof supports; a main source and a pilot source of fluidpressure; a main pressure conduit pressurized from said main source andoperatively connected to the several roof supports to effect theiradvance; each roof support including at least onefluid-pressure-operated prop to which the main pressure conduit isconnected, and a control valve operable to cause its roof support toundergo an advancing operation; a pilot pressure conduit operativelyconnected between the pilot pressure source and the control valves ofthe several roof supports in sequence; each control valve being arrangedto send a fluid pressure signal along the pilot pressure conduit fromits own roof support to the control valve of the next roof support, uponcompletion of the advancing operation of its own roof support, toinitiate an advancing operation of the next roof support; a warningdevice connected to the main pressure conduit and operable by departureor pressure therein from its normal range of fluctuation occurringduring an advancing operation, to indicate interruption of suchadvancing operation; and means operatively connected to said warningdevice to delay its indication during normal pressure fluctuations, buteifecting such indication in the event of a continuing abnormal pressurein the main pressure conduit.

3. A roof support assembly as in claim 2, wherein the warning deviceincludes pressure-sensitive means shiftable under the influence ofpressure in the main pressure conduit, from a null position towards amaximum position, but arranged to remain between such positions underthe influence of normal pressure fluctuations in said main pressureconduit during an advancing operation, and a warning signal arranged foroperation by said pressuresensitive means upon its reaching its maximumposition under the influence of maximum pressure in the main pressureconduit occurring as a result of stoppage of an advancing operation.

4. A roof support assembly as in claim 3 wherein the delaying means isoperatively interposed between the pressure-sensitive means and theWarning signal, to delay operation of the latter unless thepressure-sensitive means remains in its maximum position for apredetermined period of time.

5. A roof support assembly as in claim 3, wherein the Warning deviceincludes means operable by the pressuresensitive means when the latteris in its null position, and arranged to operate the warning signal whenthe pressure sensitive means remains for a predetermined period of timein its null position.

6. A roof support assembly as in claim 5, wherein the delaying means isoperatively interposed between the last- 8 mentioned means and theWarning signal, to prevent actuation of said signal during momentarymovement of the pressure-sensitive means to its null position.

'7. A roof support assembly as in claim 2, including a connection fromthe pilot pressure conduit to the Warning device, said warning deviceincluding a pressure gauge movable from a 'null position towards amaximum position by pressure in the main pressure conduit, anelectrically operable warning signal, an electric circuit including aswitch closable by the pressure gauge in its maximum position, and alsoincluding the time delay means and the warning signal, and a switch insaid circuit biased to open, but arranged to be closed by pressure inthe pilot pressure conduit.

8. A roof support assembly as in claim '7, the circuit also including aswitch arranged to be closed by the pressure gauge when the latter is inits null position, and a by-pass connection from said latter switchdirectly to the time delay means and the warning signal, by-passing thepilot-pressure'operated switch, to energize the warning signal by thepressure drop in the main pressure conduit when no advancing operationis occurring.

References Cited by the Examiner UNITED STATES PATENTS 758,819 5/1904Callum 340-227 2,749,536 6/1956 Sperling 20083 2,959,156 11/1960 Dreptin91-l 3,045,627 7/1962 Eek 73407 SAMUEL LEVINE, Primary Examiner.

FRED E. ENGELTHALER, Examiner.

1. A ROOF SUPPORT ASSEMBLY INCLUDING A SERIES OF FLUIDPRESSURE-OPERATED ADVANCEABLE ROOF SUPPORTS, A SOURCE OF FLUID PRESSURE, A CONDUIT CONNECTING SAID SOURCE WITH EACH ROOF SUPPORT EACH ROOF SUPPORT INCLUDING AT LEAST ONE FLUID-PRESSURE-OPERATED PROP TO WHICH SAID CONDUIT IS CONNECTED, AND A FLUID-PRESSURE-OPERATED MEANS TO ADVANCE IT ALSO CONNECTED TO SAID CONDUIT, AND A CONTROL VALVE ASSEMBLY INDIVIDUAL TO EACH ROOF SUPPORT AND OPERABLE TO SUPPLY PRESSURE FLUID FROM SUCH SOURCE TO CAUSE ITS ROOF SUPPORT TO UNDERGO AN ADVANCING OPERATION, EACH CONTROL VALVE ASSEMBLY BEING ARRANGED TO SEND A SIGNAL TO THE CONTROL VALVE ASSEMBLY OF THE NEXT ROOF SUPPORT, TO INITIATE ADVANCE THEREOF, UPON COMPLETION OF THE ADVANCE OF ITS OWN ROOF SUPPORT, A WARNING DEVICE INCLUDING A PRESSURE SENSITIVE MEANS OPERATIVELY CONNECTED TO SAID CONDUIT AND OPERABLE BY DEPARTURE OF PRESSURE THEREIN ITS NORMAL RANGE FLUCTUATION OCCURING DURING AN ADVANCING OPERATION, TO INDICATE INTERRUPTION OF SUCH OPERATION, AND TIME DELAY MEANS OPERATIVELY DURING SUCH NORMAL PRESSURE MEANS TO DELAY ITS INDICATION DURING SUCH NORMAL PRESSURE FLUCTUATIONS, BUT ABNORMAL PRESSURE IN SAID CONDUIT. 